Tool holder and method for producing a tool receiving portion for such a tool holder

ABSTRACT

A tool holder with a main part, a deformable receiving portion for clamping a tool, and at least one blocking element which is designed to engage into a corresponding counter element on the tool in order to prevent the tool from moving axially out of the tool holder. The at least one blocking element is integrally formed with the receiving portion. A clamping system having such a tool holder and a method for producing a receiving portion for such a tool holder are also described.

FIELD OF THE DISCLOSURE

This disclosure relates to a tool holder for clamping tools by friction.The disclosure also relates to a clamping system with a tool holder ofthis kind, and also to a method for producing a tool receiving portionfor such a tool holder.

BACKGROUND OF THE DISCLOSURE

Already known from WO 2007/118626 A1 is a tool holder with an expansionsleeve deployed within a main part, the expansion sleeve being formed toreceive a tool and capable of being compressed with hydraulic fluid toclamp the tool in place. The tool holder further includes a safety catchthat contains multiple corresponding counter elements to engage with theblocking elements deployed in the main part, in order to prevent theaxial slippage of the tool during the processing. In this known toolholder, the blocking elements are realized as bolts or balls that canslide into corresponding drilled holes in the main part, and engage withcorresponding clamping grooves on the shank of a tool to be clamped. Inthis tool holder, however, the main part must be handled in atime-consuming way to release the blocking elements.

SUMMARY OF THE DISCLOSURE

The disclosure produces a tool holder of the above-described kind, aswell as a clamping system with such a tool holder, that is simpler toproduce and easy to assemble.

Preferred refinements and advantageous configurations of the disclosureare also disclosed.

In the tool holder of this disclosure, the at least one blocking elementis formed integrally with the receiving portion. As a result, thereceiving portion can easily be fitted together with the blockingelements. In addition, the blocking element does not take any space awayfrom the receiving portion. The entire available space can be used bythe receiving portion, so that there is no loss of clamping force.

The clamping system of the disclosure comprises a tool holder and atool, the tool holder comprising a main part, a deformable receivingportion for clamping a tool, and at least one blocking element formedintegrally with the receiving portion, which engages with acorresponding counter element to prevent the tool from slipping axiallyout of the tool holder.

In an especially preferred embodiment, the receiving portion is anexpansion sleeve deployed in a receiving opening of the main part andsubject to external pressure with hydraulic fluid, on the inner side ofwhich is deployed the at least one blocking element.

The receiving portion can however also be a contracting chuck, a rollingpower chuck, a reducing sleeve deployed within a clamping chuck, or acollet chuck that can be deformed by a clamping element and deployedwithin a receiving opening of the main part, on the inner side of whichis deployed the at least one blocking element; or another frictionalclamping system.

In an embodiment that is both advantageous in production terms and easyto assemble, the at least one blocking element can be formed directly onthe receiving portion. The blocking element can, however, in the case ofan expansion sleeve, also be a separate component implemented as a ball,bolt, etc., fastened to the expansion sleeve.

The receiving portion can be produced from ceramic, metal, or a mixtureof the two.

For direct forming of the blocking element on the receiving portion, thereceiving portion according to this disclosure is preferably producedfrom a metallic solid material by a material-removal method by producinga recess; in the production of the recess to form the blocking elementthat is formed integrally with the receiving portion, at least oneprotrusion projecting into the recess is left out. The blocking elementis thus formed as one unit with the receiving portion. The spark erosionmethod, as well as the method known under the abbreviation EDM(“electrical discharge machining”) and/or electrochemical removalmethods like that known under the abbreviation ECM (“electrochemicalmachining”), or a combination thereof, such as ECDM (“electrochemicaldischarge machining”), have been found to be especially advantageous forproducing the receiving portion from a metallic solid. With suchmetal-removing methods, the complex structures for forming projectionsthat project inward within the receiving portion, and which form theblocking elements of the disclosure, can be produced. Thus, for theproduction of the recess in a solid block, machining methods can firstbe applied in a first processing step, and material-removing sparkerosion methods, as are known under the abbreviation EDM (“electricaldischarge machining”), and/or electrochemical removal methods, in aconcluding processing step, whereby the fine structures can then beshaped for forming the projections in the recess that form the blockingelements. Obviously, the recess can also be produced entirely by meansof machining methods.

In an especially advantageous embodiment, the at least one blockingelement is realized in the receiving portion as a projection thatstretches inward to engage with the corresponding recess on the shank ofa tool to be clamped; this projection being preferably formed integrallywith the receiving portion, and, as described above, produced in arecess of a solid block via a material-removing spark erosion methodand/or an electrochemical removal method. Likewise, the block elementfurnished in the receiving portion could, however, also be realized as arecess, the corresponding counter element on the tool could be realizedas a projection. The blocking element can have a semi- orpartially-circular-shaped cross section for more straightforwardengagement with the corresponding counter element.

In a preferred manner, the at least one blocking element can extend overat least a partial circumference of the receiving portion on the innerside thereof, in the manner of a female thread. A more even mountingalong the circumference can be achieved by deploying multiple blockingelements along at least a partial circumference of the receivingportion, in the manner of a female thread. In the case of multipleblocking elements, the blocking elements are preferably set apart atequal angles in the peripheral direction within the receiving portion.

In an alternative method of production, the receiving portion can alsobe produced from ceramic or metal powder by compression molding or lasersintering.

BRIEF DESCRIPTION OF THE DRAWINGS

Additional distinguishing characteristics and advantages of thedisclosure will be apparent from the following description of apreferred embodiment with reference to the drawings. The drawings are asfollows:

FIG. 1 a tool holder with an expansion sleeve for hydraulic clamping ofa tool, in a longitudinal section view;

FIG. 2 enlarged partial view of the expansion sleeve of FIG. 1;

FIG. 3 perspective view of the expansion sleeve;

FIG. 4 view of the expansion sleeve from behind;

FIG. 5 detail view of the expansion sleeve in a partial cutaway view;

FIG. 6 detail A of FIG. 2;

FIG. 7 partial perspective view of a first embodiment of a clampingsystem with tool holder, expansion sleeve and tool;

FIG. 8 partial perspective view of a second embodiment of a clampingsystem with tool holder and tool;

FIG. 9 partial perspective view of a third embodiment of a clampingsystem with tool holder, reducing sleeve and tool;

FIG. 10 partial perspective view of a fourth embodiment of a clampingsystem with tool holder, collet chuck, and tool; and

FIG. 11 partial perspective view of a fifth embodiment of a clampingsystem with tool holder, rolling power chuck, and tool.

DETAILED DESCRIPTION OF THE DISCLOSURE

FIG. 1 shows a longitudinal section of a tool receiving portion 1, shownhere as a hollow-taper-shank (HSK) tool receiving portion, with arotationally symmetric main part 2 and an expansion sleeve 3 deployedwithin the main part 2 to receive the cylindrical shank of a tool, notshown here. The main part 2 has a cylindrical front part 4 with areceiving opening 5 for the expansion sleeve 3 and a conical rear part 6for accommodating the work spindle of a machine tool. Between thecylindrical front part 4 and the conical rear part 6 is furnished agripper groove 7 on the outer side of the main part 2.

The expansion sleeve 3 shown separately in FIG. 2 has on its exteriortwo circumferential recesses 8 set apart from one another, and a coil 9on its front end. Between the recesses 8 and the interior wall of themain part 2 in the vicinity of the receiving opening 5, the pressurechambers 10 shown in FIG. 1 are delimited to receive hydraulic fluid.The expansion sleeve 3 is preferably fastened to the main part 2 at thefront and back ends of the sleeve. It can be soldered thereto orfastened to the main part 2 in another way. The pressure chambers 10 aree.g. connected to a pressure space deployed within the main part 2 viachannels not shown here, also within the main part 2, the volume of thepressure space being adjustable e.g. by a partition that can be moved bya screw. By moving the partition by means of the screw, the pressure ofthe hydraulic fluid in the pressure space and pressure chambers 10 canbe elevated, thereby pushing the expansion sleeve 3 inward radially.Through this arrangement, which is well-known and therefore not shown,the expansion sleeve 3 is uniformly pressed against the cylindricalshank introduced into the expansion sleeve 3, thus enabling a centricclamping over the full surface, with a high level of clamping force.

On the interior side of the expansion sleeve 3 are furnishedinward-projecting blocking elements 12 in a back region 11 with anexpanded inner diameter, which run in the manner of a female thread andarrive at a cylindrical shank 14 of a tool 15, shown in FIG. 7, toengage with a corresponding counter element 13. The counter elements 13are realized in the manner of a male thread. By means of the blockingelements 12 that engage with the corresponding counter element 13 on thetool 15, a safety catch is formed that prevents e.g. axial slippage ofthe tool 15 due to e.g. vibration during processing.

In the embodiment shown, the blocking elements 12 are realized asprojections running helically in the peripheral direction, with asemicircular cross section. As evident from FIG. 4, in the embodiment,there are furnished three projections set apart at equal angles in theperipheral direction, in the form of female threads as blocking elements12 that run in the manner of a triple inner female thread with a pitchangle on the inner wall of the expansion sleeve 3. The counter elementsthat fit into the blocking elements 12 are formed as clamping groovesthat run helically, in the manner of a triple male thread on theexterior of the cylindrical shank 14 of a tool 15, along thecircumferential surface starting on the rear face.

The expansion sleeve 3 is preferably produced according to the method ofthe disclosure from a solid metallic block (e.g. a solid cylinder) byproducing a recess by means of a material-removing spark erosion process(like e.g. EDM or ECDM); the blocking elements 12, as projectionsextending inward in the cylindrical recess, are omitted in forming therecess.

To grip a tool in the tool holder 1, the tool must first be turned uponintroduction into the tool holder 1 in such a way that the blockingelements 12 on the expansion sleeve 3 are able to engage with thecorresponding counter elements 13 on the tool 15. The expansion sleeve 3can then be compressed from outside with hydraulic fluid. By means ofthis pressure, the expansion sleeve 3 is pressed inward, clamping thetool 15. Axial slippage of the tool 15 out of the tool holder 1 can beprevented via the positive-fit engagement of the blocking elements 12 inthe corresponding counter elements 13.

FIG. 7 shows a clamping system with a tool holder 1, an expansion sleeve3, and a tool 15 formed e.g. as a cutter or drill. In distinction fromthe embodiment of FIGS. 1-6, the expansion sleeve 3 has on its exterioronly a recess 8 for forming a pressure chamber 10. Also furnished inthis embodiment are inward-extending blocking elements 12 on theinterior of the expansion sleeve 3, in the form of helically runningprojections for engaging with the counter elements 13 on the shank 14 ofa tool 15, which are realized as clamping grooves.

FIG. 8 shows a clamping system with a tool holder 1, and a tool 15formed as a cutter or drill. In this embodiment, the receiving portionis formed as a contracting chuck 16 realized integrally with the mainpart 2. In such a tool holder 1, the contracting chuck 16 is heated byinductive heating, whereby the interior diameter of the contractingchuck 16 is expanded. While it is in a heated state, a tool 15 isinserted into the contracting chuck 16; the relationship of the innerdiameter of the contracting chuck 16 to the outer diameter of the toolshank 14 is designed so that the tool 15 is held firmly in thecontracting chuck 16 when the contracting chuck 16 is subsequentlycooled. Furnished in this embodiment are inward-extending blockingelements 12 on the interior of the contracting chuck 16, in the form ofhelically running projections for engaging with the counter elements 13on the shank 14 of a tool 15, which are realized as clamping grooves.

In a further embodiment shown in FIG. 9, the receiving portion islikewise realized as a contracting chuck 16, realized integrally withthe main part 2. Here, the tool 15 is however clamped within thecontracting chuck 16 via a reducing sleeve 17. The reducing sleeve 17 isformed in a known way as a slotted sleeve with multiple axial slots andan inner diameter adapted to the outer diameter of a tool shank 14. Onits interior, the reducing sleeve 17 likewise has inward-extendingblocking elements 12, in the form of helically running projections thatengage with the counter elements 13 on the shank 14 of a tool 15, whichare realized as clamping grooves. The reducing sleeve 17 furtherincludes on its exterior clamping grooves 18 that run helically toengage with blocking elements 19 that are formed as projectionsprojecting inward and running helically on the interior of thecontracting chuck 16. By this means, a safety catch is realized forpreventing the axial slippage of the reducing sleeve 17.

FIG. 10 shows a further embodiment wherein the receiving portion isformed as a collet chuck 22 that can be deformed by a clamping element21 and is deployed within a receiving opening 20 of the main part 2. Thecollet chuck 22 has an outer conical surface 23 for contacting an innerconical surface 24 of the receiving opening 20. The conical surfaces 23and 24 are coordinated with one another in such a way that the colletchuck 22 can be compressed inward by axial displacement, and therebygrips the shank 14 of a tool 15. On its interior, the collet chuck 22likewise has inward-extending blocking elements 12, in the form ofhelically running projections that engage with the counter elements 13on the shank 14 of a tool 15, which are realized as clamping grooves.Axial displacement of the collet chuck 22 is achieved by means of theclamping element 21, that here is realized as a ring nut screwed onto anoutside thread on the front end of the main part 2.

The tool holder 1, in a further embodiment shown in FIG. 11, may also berealized as a rolling power chuck. The main part 2 has, in a front part,a clamping region 25 furnished with lengthwise slots, as a receivingportion for the shank 14 of the tool 15. In the deformable clampingregion 25 is deployed a clamping nut 27 that is rotatably seated,usually by means of a needle bearing 26 or another ball bearing, by therotation of which a clamping pressure can be brought to bear on thedeformable clamping region 25. The needle bearings 28 seated within abearing cage shift, when the clamping nut 27 is turned on the taperinginner surface of the clamping nut 27 and a narrowing outer surface ofthe deformable clamping region 25, in such a way that when the clampingnut 27 is tightened, the clamping nut 27 presses against the deformableclamping zone 25 via the needle bearings 28 to press the deformableclamping zone 25 against the shank 14 of the tool 15. In the embodimentshown, the inward-extending blocking elements 12 are likewise formed ashelically-running projections for engaging with the counter elements 13on the shank 14 of a tool 15, which are realized as clamping grooves.The clamping elements 12 are here deployed on the interior of thedeformable clamping region 25. It is, however, also possible to deploythe blocking elements 12 further within the main part 2. In addition, areducing sleeve, as shown in FIG. 9, could be deployed between thedeformable clamping region 25 and the tool shank 14.

The disclosure is, of course, not limited to HSK tool holders. SK, JIS,BT, ABS, or Capto interfaces, and the like, can similarly be furnishedon the main part 2.

The clamping elements do not necessarily have to be deployed in thedeformable region of the receiving portion. They can also be in anon-deformable region or in the region of the base holder.

1. Tool holder with a main part, a deformable receiving portion forclamping a tool and at least one blocking element that is formed toprevent axial slippage of the tool from the tool holder by engaging witha corresponding counter element on the tool, wherein the at least oneblocking element is formed integrally with the receiving portion. 2.Tool holder according to claim 1, wherein the receiving portion is anexpansion sleeve deployed in a receiving opening of the main part andsubject to external pressure with hydraulic fluid, on the inner side ofwhich is deployed the at least one blocking element.
 3. Tool holderaccording to claim 1, wherein the receiving portion is formed as acontracting chuck realized integrally with the main part, on the insideof which is deployed the at least one blocking element.
 4. Tool holderaccording to claim 1, wherein the receiving portion is formed as areducing sleeve deployed within a contracting chuck, on the inside ofwhich is deployed the at least one blocking element.
 5. Tool holderaccording to claim 1, wherein the receiving portion is formed as acollet chuck that is deployed within the a receiving opening of the mainpart and can be deformed by a clamping element, on the inside of whichis deployed the at least one blocking element.
 6. Tool holder accordingto claim 1, wherein the receiving portion is formed as a clamping regiondeployed on a front part of the main part, that can be deformed by aclamping nut seated on the main part in such a way that it can berotated by a roller bearing.
 7. Tool holder according to claim 1,wherein the at least one blocking element is formed as aninward-extending projection.
 8. Tool holder according to claim 1,wherein the blocking element has a semicircular or partially circularcross section.
 9. Tool holder according to claim 1, wherein at least oneblocking element can stretch at least over a partial circumference ofthe receiving portion on the inner side thereof, in the manner of afemale thread.
 10. Tool holder according to claim 1, wherein multipleblocking elements running at least over a partial circumference of theexpansion sleeve are deployed on the inside of the receiving portion.11. Tool holder according to claim 10, wherein the multiple blockingelements are deployed set apart from one another at equal angles in thereceiving portion in their peripheral direction.
 12. Tool holderaccording to claim 1, wherein the receiving portion includes ceramic,metal, or a mixture of the two.
 13. Clamping system with a tool holderand a tool, wherein the tool holder includes at least a blocking elementthat is configured to prevent the axial slippage of the tool from thetool holder by engaging with a corresponding counter element on the toolwherein the tool holder is configured according to claim
 1. 14. Methodof production for a deformable receiving portion for clamping a tool,which can be inserted into or is formed integrally with a main part of atool holder, wherein the receiving portion comprises at least oneblocking element that is formed to prevent axial slippage of the toolfrom the receiving portion by engaging with a corresponding counterelement on the tool, wherein the receiving portion is produced from ametallic solid material by producing a recess by a material-removingmethod, wherein in the process of forming the recess for forming ablocking element formed integrally with the receiving portion, at leastone projection projecting into the recess is omitted, or a cavity isformed in the receiving portion.
 15. Method according to claim 14,wherein the material-removing method is a spark-erosion method and/or anelectrochemical removal method.
 16. Method of production for adeformable receiving portion for clamping a tool, which can be insertedinto or is formed integrally with a main part of a tool holder, whereinthe receiving portion comprises at least one blocking element that isformed to prevent axial slippage of the tool from the receiving portionby engaging with a corresponding counter element on the tool, whereinthe receiving portion is produced from a ceramic and/or metal powderthrough pressure-molding or laser sintering.